Download GCE Biology BY5 1075-01

WJEC 2014 Online Exam Review
GCE Biology BY5 1075-01
All Candidates' performance across questions
Question Title
1
2
3
4
5
6
7
8
N
5207
5207
5211
5210
5192
5207
5202
5194
Mean
4.4
2.9
5.2
6.8
6.2
6
6.6
4.5
SD
1.9
1.5
1.6
2.5
3.1
2
2.8
2.1
Max Mark
8
6
8
11
12
12
13
10
FF
55.5
47.8
65
61.7
51.7
50.1
51
44.8
Attempt %
99.9
99.9
100
99.9
99.6
99.9
99.8
99.6
GCE Biology BY5 1075-01
8
44.8
7
51
Question
6
50.1
5
51.7
4
61.7
3
65
2
47.8
1
55.5
0
10
20
30
40
50
60
Facility Factor %
70
80
90
100
5
6
7
14
5. The techniques of recombinant DNA technology and micro-propagation are used to produce
Genetically Modified Crops. The following summary is adapted from an account given on the
Food Standards Agency’s web site [www.food.gov.uk]
1.
A plant with the desired characteristic is identified – e.g. resistance to the herbicide
‘Roundup’.
2. The specific gene that produces this characteristic is found in the plant’s DNA and
cut out.
3. To get the gene into the cells of the plant being modified, the gene needs to be
attached to a carrier. A piece of bacterial DNA called a plasmid is joined to the gene
to act as the carrier.
4. Once the gene is attached to the plasmid, a marker gene is also added to identify
which plant cells take up the new gene.
5.
6. A copy of the ‘gene package’ is dried onto a gold or tungsten particle – and fired
into a piece of tissue from the plant being modified. The particle carries the ‘gene
package’ into the plant’s cells.
7. The plant tissue is put into a selective growth medium so that only modified tissue
develops into plants.
(a) Explain how different types of enzymes are used in stages 2 and 3 to produce the ‘gene
package’.[4]
The ‘gene package’ is put in a bacterium, which multiplies, to create many copies of
the ‘gene package’.
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(b)
Describe the steps involved in the culture of a large number of genetically identical plants
from the plant tissue produced in stage 7.
[3]
Examiner
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(i) Explain the advantage to farmers of having crops resistant to ‘Roundup’.
(c)
[3]
(ii) Explain why environmentalists might have legitimate objections to using GM crops
resistant to ‘Roundup’.
[2]
12
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17
6. A species of mouse Peromyscus polionotus found in Florida, USA, has a number of different
coat colours. Coat colour in mice is controlled by several genes. Dark fur is produced when the
hair producing cells secrete a pigment called eumelanin. A high level of eumelanin is produced
when a transmembrane protein called MC1R is stimulated by a hormone.
(a)
The diagram below shows part of the amino acid sequence of MC1R, part of the sequence
of nucleotides in the gene for MC1R and how it might change to produce light fur:
Original
Amino acid sequence
Nucleotide sequence
(allele R)
lle
Thr
Lys
Asn
Arg
Asn
Leu
His
Ser
ATCACCAAAAACCGCAACCTGCACTCG
Changed to produce light fur
Amino acid sequence
Nucleotide sequence
(allele C)
lle
Thr
Lys
Asn
Cys
Asn
Leu
His
Ser
ATCACCAAAAACTGCAACCTGCACTCG
(i) Describe the change in the gene and the subsequent change in the MC1R
molecule.[2]
(ii) Using the information provided, explain how this change results in mice with light
fur.[2]
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(b) This change in the MC1R gene means that there are two alleles, R and C.
The map below shows the distribution of the different coloured mice and the relative
frequencies of the alleles R and C in each population.
Northern Florida
sandy beaches
forest/scrub
Allele
frequency
5% R
95% C
Population 3
Allele
frequency
30% R
70% C
Population 2
Allele
frequency
100% R
0% C
Population 1
(i) Use the diagram to suggest how fur colour is related to environmental conditions.
[2]
(ii) Under what circumstance could the difference between the allele frequencies
in populations 2 and 3 be explained by genetic drift, despite both living on
beaches?[1]
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(iii) Explain how Natural Selection could have caused the relative allele frequency
shown in population 3.[4]
Examiner
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(iv) Under what circumstances would the mouse population become a separate
species?[1]
12
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19
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7.
The following is a quotation from an ecological investigation.
“Lowland heaths are high-profile ecosystems for conservation action in England, but they are
under threat from invasion by Betula spp., Pinus sylvestris, and Ulex europaeus.”
[R.J. Mitchel et al. Journal of Applied Ecology, 1997, 37, 1426-1444]
(a)
Distinguish between primary succession and secondary succession.
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[2]
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The authors studied a number of heathland sites in Dorset including Arne, Blackhill, and Higher
Hyde, where succession to one or another of the three species had taken place. The data below
are based on the paper but have been simplified and modified for illustrative purposes.
The successional stages in the study were named according to the dominant invasive species;
plus B, where Betula spp, was the invader, plus PS, where Pinus sylvestris was the invader and
plus U, where Ulex europaeus, was the invader.
(b) The group examined changes in soil chemistry from the original heath stage. Some of
their results are summarised in the table below:
soil chemical property
value by succession stage
original heath
plus B
plus PS
plus U
Arne
3.63
4.01
3.60
3.63
Blackhill
3.52
3.66
3.48
3.54
Higher Hyde
3.53
5.06
3.51
3.47
3.56
4.24
3.53
3.55
Arne
2.41
3.85
2.69
3.16
Blackhill
4.15
4.91
3.79
4.55
Higher Hyde
5.08
5.35
3.55
4.76
3.88
4.70
3.34
4.16
Arne
0.51
0.65
0.59
1.16
Blackhill
0.84
0.88
0.97
2.31
Higher Hyde
0.69
0.98
1.17
3.64
0.68
0.84
0.91
2.37
pH
mean
phosphorus μgPg
–1
mean
nitrate/nitrite μgNg –1
mean
(i) What do the pH values tell us about the soil in all stages in all sites?
[1]
..................................................................................................
(ii)Use mean values from the table above to compare three changes to soil chemistry
following invasion by Betula spp. with the changes following invasion by Ulex
europaeus.[3]
pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
phosphorus
nitrate/nitrite
................................................................................................................................................................
..............................................................................................................................................................
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Examiner
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(c) The table below shows changes to the vegetation in the successional stages:
Species
(by successional stage)
% cover of species (by site)
Arne
Blackhill
Higher Hyde
original heath
Calluna vulgaris
Erica cinerea
Erica tetralix
Cladonia portentosa
62.0
22.4
9.9
8.5
66.1
25.7
2.6
0
88.2
2.6
9.9
0.5
plus B
Betula spp.
Agrostis curtisii
Pteridium aquilinum
Calluna vulgaris
18.9
0.0
25.2
0.0
11.7
53.6
7.5
0.0
16.5
0.0
1.6
0.4
plus PS
Pinus sylvestris
Pteridium aquilinum
Erica cinerea
Calluna vulgaris
36.2
0.3
0.0
0.0
38.2
24.7
0.0
0.0
plus U
Ulex europaeus
Calluna vulgaris
Erica cinerea
Erica tetralix
87.0
14.7
1.5
0.1
75.3
5.8
11.3
0.3
79.0
7.2
4.3
0.3
(i) Which invading species has least impact on the vegetation on the original
heathland?[1]
(ii)
With reference to the data for plus B in both tables suggest a mechanism by which
changes to vegetation occur during succession.
[2]
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(d)
Sixteen years later some of these successions have reached their natural conclusions.
(i)
Examiner
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What name is given to the group of organisms that inhabit the ecosystem at the end
[1]
of successional change?
(ii) What usually happens to species diversity as succession proceeds?
[1]
(iii)Using named species from the table in part (c) explain why conservationists in
Dorset are taking steps to prevent plus B and plus PS succession in heathland,
but are less worried about type plus U succession.
[2]
13
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